You need to join these two datasets together to make one dataset. The easiest way to do this is with Magic ETL. The below example shows you more than just joining, but the idea is that you can use the join tile to join your two datasets together. You would join on week. You might want to review this KB article to better understand the different types of joins if you are unfamiliar with the concept.

ETL Actions: Combine Data

https://knowledge.domo.com/Prepare/Magic_Transforms/ETL_DataFlows/ETL_Actions%3A_Combine_Data#Join_Data

Learn how to combine data in Magic ETL using the Append Rows and Join Data actions.

Sorry @GrantSmith and @MarkSnodgrass hard disagree.

Don't JOIN the data. APPEND them.

If you get to the point where you have multiple rows per week OR if dataset 1 is at a different granularity than dataset2 then you end up with row growth (because you're JOINING) and you have to crazy math to 'SUM DISTINCT).

1) add a constant "Activity Type" to each dataset so you know what type of metric you're dealing with

2) duplicate the date column and call it "Activity Date" for both datasets. (then use Activity Date in Analyzer).

3) UNION the data

https://www.youtube.com/watch?v=PVbOeLSae9o&t=772s